1. Field of the Invention
The present invention relates to a rotating device including a shaft body and a bearing body supporting the shaft body in a relatively rotatable manner.
2. Description of the Related Art
Rotating devices like a disk drive device are becoming compact and increasing the capacity thereof, and are built in various electronic devices. Such rotating devices are popularly built in, in particular, a hard disk drive that is a kind of disk drive devices of portable electronic devices, such as a laptop computer and a portable music player. The rotating devices like the disk drive device built in such portable electronic devices require improved shock resistance and vibration resistance (hereinafter, referred to as “vibration resistance characteristic, etc.,”) so as to withstand a shock due to falling and a vibration when carried in comparison with the rotating devices built in stationary electronic devices like a desktop computer. Moreover, such rotating devices require thinning and weight saving in comparison with the rotating devices built in the stationary electronic devices like a desktop computer. In general, thinning and improvement of the vibration resistance characteristic, etc., are in a trade-off relationship.
One of the inventors of the present invention proposes a rotating device that is a disk drive device having a fluid dynamic bearing mechanism formed between a shaft body and a bearing body, and having the shaft body including a shaft fixed to a base in, for example, JP 2010-261580 A. According to the rotating device disclosed in JP 2010-261580 A, a radial dynamic bearing is formed in a space in the radial direction between the shaft body and the bearing body, and a thrust dynamic bearing is formed therebetween in a space in the axial direction.
In the case of the rotating device that is a disk drive device disclosed in JP 2010-261580 A, in order to improve the vibration resistance characteristic, etc., it is necessary to improve the rigidity of the radial dynamic bearing (hereinafter, referred to as a “radial rigidity”). To improve the radial rigidity, there is a scheme of making a space narrower in the radial direction between the shaft body and the bearing body both configuring a radial bearing. However, in the case of such a rotating device, if the space between the shaft body and the bearing body is too small, the shaft body and the bearing body contact with each other when the rotating device is rotating, disturbing the rotation thereof, and in the worst case, the shaft body and the bearing body are highly possibly damaged.
Moreover, in order to improve the radial rigidity, there is another scheme of extending the upper end or the lower end of a region where the radial dynamic bearing is formed in the axial direction so as to elongate the axial span of the radial bearing. However, in the case of the above-explained rotating device, an air-liquid interface in a capillary seal formed at the outer periphery of the flange 15, a thrust dynamic pressure generating part formed in a space between the flange 15 and the sleeve 14, and the upper end of the region where the radial dynamic bearing is formed are disposed in this order in the axial direction. That is, the upper limit of the upper end of the region where the radial dynamic bearing is formed is restricted by the flange 15.
Under such a circumstance, the restriction of the upper end of the region where the radial dynamic bearing is formed by the flange disturbs the improvement of the radial rigidity, and thus disturbing the improvement of the vibration resistance characteristic, etc.
In view of such a circumstance, the inventors of the present invention recognized that it is necessary to extend the upper end or the lower end of the region where the radial dynamic bearing is formed in the axial direction in order to improve the vibration resistance characteristic, etc., of the rotating device.
Such a technical issue arises in the case of the rotating device built in not only a portable electronic device but also other kinds of electronic devices.
The present invention has been made in view of such a circumstance, and it is an object of the present invention to accomplish both thinning and improvement of the vibration resistance characteristic, etc.